Method and apparatus for sealing binding using ultrasonic or radio frequencies

ABSTRACT

A METHOD FOR WELDING THE PLURAL FINGERS OF A PLASTIC BINDING ELEMENT TO THE BACKBONE OF THE BINDING ELEMENT IN A SIMPLE MANNER FOLLOWING THE ASSEMBLY OF A MULTIPLICITY OF SHEETS OF PAPER OR THE LIKE UPON THE BINDING ELEMENT COMPRISING PROVIDING A BACKING ELEMENT FOR THE BACKBONE AND INSERTING A PROBE GENERALLY TRANSVERSELY PAST THE FINGERS TO HOLD THE OVERLYING END OF THE FINGER AGAINST THE BACKBONE AND THEN APPLYING ENERGY TO THE AREA OF LAPPING COMPRISING EITHER ULTRASONIC VIBRATIONS OR RADIO FREQUENCY ENERGY TO WELD THE ENDS OF THE FINGER TO THE BACKBONE.

A ril 27, 1971 H N, sTAA-rs ETAL 3,576,690

METHOD AND APPARATUS FOR SEALING BINDING USING ULTRASONIC OR RADIO FREQUENCIES Original Filed July 30, 1965 2 Sheets-Sheet 1 {1 90 J ar/z's-sley TTORNE YS P 27, 1.971 H. N. STAATS ETAL 3,576,

METHOD AND APPARATUS FOR SEALING BINDING USING ULTRASONIC OR RADIO FREQUENCIES Original Filed July 30, 1965 2 Sheets-Sheet 2 INVENTORS A e/W'y /V 6200/6 ya/rbe Q [er/X0 I 90/ /V0//(fs's*e ATTORA/Eg United States Patent METHOD AND APPARATUS FOR SEALING BINDING USING ULTRASONIC 0R RADIO FREQUENCIES Henry N. Staats, Deerfield, Maurice D. Levitan, Wilmette,

and Neal J. Morrissey, Chicago, Ill:, assignor to General Binding Corporation, Northbrook, Ill.

Original application July 30, 1965, Ser. No. 476,097. Divided and this application Aug. 1, 1969, Ser. No. 861,531

Int. Cl. B29c 27/04 U.S. Cl. 156273 Claims ABSTRACT OF THE DISCLOSURE A method for welding the plural fingers of a plastic binding element to the backbone of the binding element in a simple manner following the assembly of a multiplicity of sheets of paper or the like upon the binding element comprising providing a backing element for the backbone and inserting a probe generally transversely past the fingers to hold the overlying end of the finger against the backbone and then applying energy to the area of lapping comprising either ultrasonic vibrations or radio frequency energy to weld the ends of the finger to the backbone.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a division of our co-pending application entitled Method and Apparatus for Sealing Bindings, Ser. No. 476,097, filed July 30, 1965, which application issued Dec. 9, 1969, as U.S. Pat. No. 3,483,067.

The present invention relates to the field of binding a plurality of perforated sheets into a booklet or the like by means of a plastic binding element. More particularly, the invention is concerned with the provision of a substantially more efficient method, binding element, and appar atus for rendering the normally loost-leaf binding element a permanent binding device.

As those familiar with the art of applying thermoplastic plastic binding elements to a plurality of perforated sheets are aware, it is occasionally desired that the binding elements be made permanent. Attempts have been made in the past by applying heat to the plastic fingers of the binding. However, whereas prior welding systems have proved satisfactory for small numbers of books being bound by hand and under rather critical temperature controls, to our knowledge no truly efiicient system has been constructed for rendering a normally loose-leaf plastic binding element permanently bound on a fast, truly massproduction basis. In accordance with the present invention, a very rapid, efiicient and relatively non-critical method and apparatus have been devised for rendering the typically loose-leaf bound booklet a permanently bound one.

In accordance with the present invention, a plurality of perforated sheets of paper or the like are bound in a looseleaf manner by means of a plastic binding element. This element comprises a thermoplastic curled binding element composed of a longitudinally extending backbone member having a plurality of transversely extending integral fingers curled into a generally circular configuration to lap the backbone. In accordance with standard practice, such plastic binding elements may readily be reopened for the addition or subtraction of perforated sheets by holding the backbone and pulling the curled fingers away from it sufficiently for the free ends thereof to accept additional sheets. By the present invention the free ends of the backbone fingers are welded by a single operation to adjacent portions of the binding element backbone.

In further accord with the invention, this welding operation takes place in a fixture that automatically aligns ICC the perforated sheets and the plastic binding element into a position in which the fingers may readily be welded to the backbone with utmost accuracy and simplicity, and that then permanently welds them as positioned.

In order to provide simple and substantially complete repeatability of positioning of the book and binding during the sealing operation, the binding is preferably constructed in a novel manner by providing its backbone of a predetermined width tailored to the punched apertures of the perforated sheets. For example, in co-operation with apertured sheets having the inner edge of the punched aperture approximately A from the outer edge of the sheet, as is considered a conventional practice, the width of the backbone would be in the general area to /2". The width of the backbone would be kept substantially constant throughout the ordinary range of standard binding sizes. This is true since the dimension of the backbone is designed for providing a suitable finger-backbone lapping condition, which condition is substantially the same independently of the length of the backbone fingers. Additioally, special fixtures are provided that are tailored to the physical configuration of the binding element to assure proper alignment of the components during the actual sealing operation.

In order to still further speed up the actual sealing of the binding, the sealing cycle is reduced to a minimum through the utilization of wave-form energy, either in the form of ultrasonic waves at a frequency generally in the range of 20 to kilocycles per second (kilohertz), or waves at radio frequencies generally in the range of 15 to 60 megacycles per second megahertz). These energy applications are termed, for convenience, ultrasonic sealing and dielectric sealing, respectively. In both instances the sealing which occurs at the interface between abutting sheets of material is accomplished with a minimum of heating at the outer peripheral surface of the material as in most prior heat sealing devices employing heated electrodes that operate to heat the interface solely by conductivity through the plastic binding element itself. Since the heating takes place extremely rapidly and substantially at the interface in the method according to the present invention, substantially smaller quantities of heat are required and, further, substantially no degradation occurs in the plastic surrounding the weld area. Accordingly, extremely rapid welding with a high efiiciency weld, is provided.

The invention takes several forms. In adidtion to a novel binding element configuration, the methods and apparatus employed in accordance with the invention embody an ultrasonic or dielectric probe element having longitudinally deflected ends for insertion between the transverse fingers of a thermoplastic binding element, and for transverse movement against a back-up bar in a position with the deflected ends of the probe tightly clamping the overlapping ends of the binding element fingers to the binding element backbone. The longitudinally deflected probes provide absolute accuracy of weld position and permit automatic shifting of the binding, where desired, in the process of positioning the binding for the sealing step. In accordance with illustrated variations in the form of the apparatus employed in the method of the present invention, the probes may be vertically downwardly extending for co-operation with a generally horizontal, upwardly facing back-up bar or the probes may be generally vertically upstanding for co-operation with a horizontal, generally downwardly facing back-up bar. Manipulation of the book being bound varies with the specific probe and backup bar arrangement. A commercially satisfactory sealed binding is, however, the result of manipulation of the apparatus in various forms.

It is, accordingly, an object of the present invention to provide a novel binding element.

Another object of the present invention is to provide a novel and substantially improved method for heat-sealing a thermoplastic binding element.

Still another object of the present invention is to provide an improved method capable of heat-sealing, by waveform energy application, thermoplastic binding elements.

A feature of the invention is the provision of the longitudinally deflected heat-sealing probe means for transversely passing the fingers of a thermoplastic binding element while providing for clamping contact between the ends of such fingers and the backbone of the binding element.

Still a further feature of the invention is the provision of a binding element having a backbone of a width on the order of to /z" for use with perforated sheets having the most remote edges of the perforations approximately 4'' from the edge of the sheet.

Still a further object of the invention is the provision of an ultrasonic heat-sealing method for permanently and extremely rapidly sealing loose-leaf binding elements of the thermoplastic type.

Still other and further objects and features of the invention will at once become aparent to those skilled in the art from a consideration of the attached specification and drawings wherein two embodiments of the invention are shown by way of illustration only, and wherein:

FIG. 1 is a generally isometric view of an apparatus for the heat-sealing of bound booklets showing a booklet in position for initiation of the heat-sealing step;

FIG. 2 is a partial cross-section takenalong the line IIII of FIG. 1;

FIG. 3 is a side-elevational view substantially enlarged, of a portion of the apparatus shown in FIG. 1;

FIG. 4 is an enlarged view generally as illustrated in FIG. 3 wherein the parts are in position for the heatsealing step;

FIG. 5 is a modified form book support and probe combination employed in a variation of the method of the present invention; and

FIG. 6 is a side-elevational View of the modified form of construction illustrated in 'FIG. 5, in the position of the heat-sealing step.

AS snow-N ON THE DRAWINGS As may be seen from a consideration of the embodiment illustrated in FIGS. 1 through 4, a booklet is provided having outermost sheets or covers :10, 11 and a plurality of enclosed sheets 12. These sheets are perforated along one edge thereof with a plurality of perforations 13 which accommodate the fingers 14 of a thermoplastic binding element generally indicated at 15. The binding element 15 is provided with a backbone 16 extending longitudinally thereof throughout its entire length and having integrally secured thereto the multiple fingers 14.

The binding and booklet above described are initially placed upon a support device generally indicated at 20 at the left-hand end designated 21 in FIG. 1. For sealing, the booklet is pushed to the right-hand end of the device in the direction of arrow 22 and into the position shown at 23 in FIG. 1. The book is separated to provide the outermost sheets in a backwardly open condition as shown in FIG. 2 prior to its placement on section 2.1 of the device 20. This separation of the book into the position shown in FIG. 2 automatically positively positions the backbone 16 between the outermost sheets and 11 and, when the booklet is thus placed upon the support 21 the overlapping ends 14a of the fingers 14 are accurately positioned immediately above the backbone 16. As thus positioned, the multi-toothed probe 25 having teeth 26 may readily pass vertically downwardly past the innermost ends of the bound sheets into clamping contact with the overlapping portions 14a of the fingers '14 and the back-up support 23'.

As may be best observed from a consideration of FIG. 3 and 4, the teeth 26 of the probe 25 are deflected longitudinally of the axis of the probe 25 in the manner illustrated at deflected ends 26m. The ends 26a are of a width smaller than the gap between adjacent fingers 14 so that downward movement of the gap between adjacent fingers 14 so that downward movement of the probe, in FIG. 3, will cause passage of the probe teeth 26 between adjacent fingers 14 until the beveled surfaces 26b contact the fingers 14. At the time of such contact, the binding element, and the sheets bound therein, are axially slid toward the right as viewed in FIG. 3 by continued downward movement of the probe 25. As the binding moves toward the right, it assumes a condition shown in FIG. 4 in which the ends 2611 of the teeth 26 are in tight contact with the overlapping ends 14a of fingers 14, clamping them tightly to the backbone 16 and against the back-up bar or support 23. With the parts in this position, heat-sealing energy may be supplied to the overlapping portions by way of the teeth 26.

We have found that a particularly advantageous technique of heat-sealing thermoplastic binding elements, for example of the polyvinyl chloride type, comprises the application of ultrasonic waves. Thesewaves, at the frequency of approximately 20 kilocycles per second (kilohertz), may be generated by any conventional ultrasonic wave-form generator having a mechanical vibration output, not forming a part of this invention per se. The energy is transmitted by contacting the said output with the clamped binding by touching the output of the binding directly (not shown), or by employing the back-up bar 23a or the finger probe 25 as the output member. It has been found that when energy is applied to the clamped plastic portions, as illustrated, that the heating takes place substantially only at the interface area between he overlapping fingers land the backbone of the binding element. This is true since the wave-form energy passes through the plastic until it strikes the interface at which 'point the energy is deflected and causes molecular vibration substantially at the interface. This molecular vibration causes heat which satisfactorily seals impact modified polyvinyl chloride or similar elements of a copolymer of polyvinyl chloride and vinyl acetate binding elements substantially instantaneously. These substances, as preferably used, have a softening or formability temperature of about F. and are resilient after forming.

In spite of the fact that the plastic used is not a rigid, extremely hard substance, such as metal, and prior techniques of ultrasonic wave-form application have strongly suggested that somt materials such as impact modified polyvinyl chloride would not prove heat-scalable, we have found that such binding elements are very successfully heat-sealed in the manner above described upon the application of ultrasonic wave-form energy to the binding when in clamped condition. In this technique, it has been found that a non-metallic backup member 23 may readily be employed since electrical conductivity of the back-up is non-essential. This is true since the ultrasonic waves appear to accomplish their heating effect at the interface and the energy may be applied at one point rather than as a part of a circuit.

As above noted, it is equally possible to provide heatsealing by way of a dielectric device employing radio frequency vibrations. In such an event, however, it is preferred that the probe 25 be of electrically conductive material, properly insulated from all surrounding areas, and, similarly, that the back-up support 23 be provided with an electrode 23a forming a part of the radio frequency wave-form generator. In view of the extremely serious losses of energy occasioned by leakage, however, it is preferred that the electrode 23a and the metallic probes 25 be electrically isolated from all surrounding materials as much as possible, and as generally illustrated in FIG. 2 where the back-up support 23 is constructed of dielectric material and the bar 23a is electrically conductive.

I11 the method and operation described in connection with the structures illustrated in FIGS. 1 through 4, a stop 23b is provided for positioning the backbone 15. This positioning accurately presents the gap between the fingers 14 to the ends 26a of the probe teeth 26. The teeth are rounded as at 26b to avoid any snagging with the fingers 14 and with the backbone positioned as shown in FIG. 3, downward movement of the probe 25 will automatically shift the binding toward the right into the sealing position. Stop 23b thus provides accurate means for manually positioning the booklet in the position shown in FIG. 1. In ordinarily practicing the method of the present invention, a book would be initially opened into the condition shown in FIG. 2 and placed upon the support portion 21 while the probe 25 is sealing a previously positioned booklet. Then, as the probe 25 is lifted, the booklet is shifted from area 23 off toward the right for reclosing and stacking while the booklet then resting upon the portion 21 is shifted to the right into position against the stop 23b. As the probe 25 is energized into the downward position, by means of a conventional mechanical press, or the like, the next booklet is opened and positioned on the support portion 21.

As has been observed above, the backbone 16 is dimensionally important to the method above described. By providing the backbone on the order of to /2" wide, it is adequately supported as illustrated in FIG. 2 and is automatically properly positioned. If the backbone were substantially greater in width, inaccurate positioning would be possible or an extremely wide and unsatisfactory support would be required. Alternatively, if the backbone were extremely narrow, substantially no accuracy whatever would be provided in the positioning.

In the embodiment of the apparatus illustrated in FIGS. 5 and 6, the probe, generally indicated at 125, is provided with upstanding teeth 126 having longitudinally, or axially, deflected portions 126a. The probe 125 has a vertical base portion 124 having rigidly secured thereto a shelf support 124a adjustably mounted upon diagonal brace 124b. The brace 12412 is adjustably mounted relative to the base 124 by way of a threaded adjusting nut 124e, permitting angular tilting of the support shelf 124a. The shelf is vertically adjustable by loosening screws 124' passing through slots 124g in bar 1242. A back-up 'bar 123 having a rigid backbone-engaging portion 123a is vertically downwardly movable for clamping engagement with the backbone 16 and lapping finger portions 14a of the fingers 14 of binding element 15. L

A plurality of vertically extending stop members 127 are rigidly secured at 128 to the support 124 and have a thickness sufliciently small to permit their passage between the adjacent fingers 14 of the binding 15. As may be seen from a consideration of FIG. 6, the combination of supports related with the stop 127 is such that axial movement of the booklet in the direction of arrow 129 causes engagement of the leading or outermost edge 16a with the stops 127 causing the binding to oscillate to a position in which the edge portion 16b of the backbone, between the fingers 14, abuts the top cover sheet At this position, due to the width of the backbone being greater than the distance between the perforations in the sheet 10, the backbone 16 remains projecting beyond the edges of the booklet in the position illustrated, in an overlapping relation with the ends 14a of the fingers 14. The back-up bar 123 may then be reciprocated vertically downwardly clamping the portions 16 and 14a upon the upper ends of deflected portions 126a of the probe teeth 126. It will be observed, accordingly, in the method employed in the welding of bindings on the apparatus of FIGS. 5 and 6, that the positioning of the backbone is again specifically determined prior to welding by a relationship with the outermost cover sheet of the booklet or other device being bound. This permits fast and very accurate component positioning, and hence, repeatability of the process.

The apparatus may be used in several manners. However, we have found a most efficient technique of operation is to provide adjustment of the shelf 124a at a level low enough to support a second booklet shown at 12a, beneath the booklet being welded. Where no such booklet is employed in the process, slowing the process down substantially, the shelf may be positioned immediately under the booklet 12. Employing the arrangement illustrated in FIG. 6, the bottom booklet 12a is one previously welded. With a thus previously welded booklet 12a positioned as in FIG. 6, the unsealed book 12 is pushed in the direction of arrow 129 until edge 16a of the backbone is against the stop 127, at which point the booklet is lowered downwardly, moving toward the left as it engages the deflected ends of the ends 126a of probe teeth 126 until it reaches the resting position upon the booklet 120. In this position the upper ends of the teeth 126 are immediately under the ends 14a of the binding element fingers 14.

The back-up bar 123 is then vertically moved downwardly clamping the backbone and fingers, at which point ultrasonic or radio frequency energy is applied by any conventional apparatus through the probe or back-up bar. As the back-up bar 123 is moved downwardly by a press or the like, and the operator is not occupied with actuation of the press, the lower booklet 12a is moved by the opera tors right hand to a stack of sealed booklets. As this operation is performed with the right hand the left hand reaches for an unsealed book, placing the unsealed book above the book being sealed. While the operator waits for the completion of the welding or sealing, the backbone is manually rolled into approximately the position shown in FIG. 6. Upon compeltion of the welding cycle, both the uppermost unwelded booklet and the then lower welded booklet are lifted upwardly and to the right, clearing the Welded booklet from the teeth 126a, and then lowered into the position shown by booklet 12a in FIG. 6. The uppermost booklet is then moved to the right starting a new sequence of motions. It has been found that an operator can seal previously bound booklets at a very rapid rate employing the sequential operation methods described in connection with the illustrated forms of apparatus in FIGS. 1 through 6.

Although no longitudinal stop has been described in connection with positioning of the book 12 to be sealed in the arrangement shown in FIG. 6, it is nevertheless clear that an axial stop at the right-hand edge of support table 124 may be provided to properly position the booklet to be sealed so that the deflected portions 1260. of the teeth of the probe 125 will be immediately under the spaces between fingers 14 at the time the booklet is initially introduced from above. Downward dropping of the booklet will then, of course, cause axially left-handed movement of the booklet by the deflection action of the portions 12611 of the teeth 126 until the uppermost portion of the teeth is immediately underneath the ends 14a of the binding element fingers 14.

From a consideration of the above specification and drawings, it will be clear that variations in apparatus and the improved method of sealing previously bound booklets, may be made without departing from the scope of the novel concepts of this invention. It is, accordingly, our intention that the scope of the invention be limited solely by that of the hereinafter appended claims.

We claim as our invention.

1. The method of welding a binding element comprising a backbone having a finger curled into lapping contact therewith and containing a plurality of perforated sheets which comprises the steps of positioning one edge of the backbone against the outermost bound sheet, placing a backing element against the backbone, inserting a probe generally transversely past the finger against the end of the finger lapping the backbone, and applying wave-form energy of a radio frequency generally of a range of 15 to 60 megahertz or of an ultrasonic frequency generally of a range of 20 to kilohertz to the areas of lapping between the probe and the backbone to weld the end of the finger to the backbone.

2. The method of welding a binding element comprising a backbone having a finger curled into lapping contact therewith and containing a plurality of perforated sheets which comprises the steps of positioning one edge of the backbone against the outermost bound sheet, placing a backing element against the backbone, inserting a probe generally transversely past the finger against the end of the finger lapping the backbone, and applying energy in the form of ultrasonic waves of a frequency generally in a range of 20 to 100 kilohertz through the probe to the area of lapping between the probe and the backbone to weld the end of the finger to the backbone.

3. The method of welding a binding element comprising a backbone and having a plurality of fingers curled into lapping contact therewith and containing a plurality of perforated sheets which comprises the steps of positioning one edge of the backbone against the outermost bound sheet, placing a backing element against the backbone, inserting a probe generally transversely past the fingers and therebetween into a position against the ends of the fingers lapping the backbone, and applying energy in the form of radio frequencies generally in the range of to 60 megahertz to the area of lapping between the probe and the backbone to weld the ends of the fingers to the backbone.

4. The method of welding a binding element comprising a backbone and having a plurality of fingers curled into lapping contact therewith and containing a plurality of perforated sheets which comprises the steps of positioning one edge of the backbone against the outermost bound sheet, placing a backing element against the backbone, inserting a probe generally transversely past the fingers and therebetween into a position against the ends of the fingers lapping the backbone, and applying energy in the form of ultrasonic waves of a frequency generally in a range of to 100 kilohertz through the probe to the area of lapping between the probe and the backbone to weld the ends of the fingers to the backbone.

5. The method of welding a binding element comprising a backbone having a finger curled in lapping contact therewith and containing a plurality of perforated sheets which comprises the steps of separating the sheets into two sections and folding them backwardly on opposite sides of the backbone such that the side edges of the backbone are positioned against and between the outermost bound sheets, resting the backbone between the outermost sheets upon a support bar, generally vertically inserting a probe past the finger and against the end of the finger, pressing the end against the backbone and the support bar, and applying energy of a radio frequency generally in a range of 15 to 60 megahertz or of an ultrasonic frequency generally in a range of 2.0 to 100 kilohertz to the area between the probe and the support bar to Weld the end of the finger to the backbone.

6. The method of welding a binding element comprising a backbone having a plurality of fingers curled in lapping contact therewith and containing a plurality of perforated sheets which comprise the steps of separating the sheets into two sections and folding them backwardly on opposite sides of the backbone such that the side edges of the backbone are positioned against and between the outermost bound sheets, resting the backbone between the outermost sheets upon a support bar, generally vertically inserting a probe past the fingers and against the ends of the fingers, pressing the ends against the backbone and the support bar, and applying energy of a radio frequency generally in a range of 15 to megahertz to the area between the probe and the support bar to weld the ends of the fingers to the backbone.

7. The method of welding a binding element comprising a backbone having a plurality of fingers curled in lapping contact therewith and containing a plurality of perforated sheets which comprises the steps of separating the sheets into two sections and folding them backwardly on opposite sides of the backbone such that the side edges of the backbone are positioned against and between the outermost bound sheets, resting the backbone between the outermost sheets upon a support bar, generally vertically inserting a probe past the fingers and against the end of the fingers, pressing the ends against the backbone and the support bar, and applying energy in the form of ultrasonic waves of a frequency generally in a range of 20 to kilohertz to the area between the probe and the support bar via the probe to weld the ends of the fingers to the backbone.

8. The method of welding a binding element comprising a backbone having a plurality of fingers curled in lapping contact therewith and containing a plurality of perforated sheets which comprises the steps of separating the sheets into two sections and folding them backwardly on opposite sides of the backbone such that the side edges of the backbone are positioned against and between the outermost bound sheets, resting the backbone between the outermost sheets upon a support bar, generally vertically inserting a probe past the fingers and against the ends of the fingers, pressing the ends against the backbone and the support bar, and applying energy of a radio frequency generally in a range of 15 to 60 megahertz to the area between the probe and the support bar via the probe to weld the ends of the fingers to the backbone.

9. A method according to claim 7, wherein the step of vertically inserting the probe includes generally horizontally shifting the probe and binding element relative to each other.

10. The method according to claim 8, wherein the step of vertically inserting the probe includes generally horizontally shifting probe and binding relative to each other.

References Cited UNITED STATES PATENTS 2,106,419 1/1938 Anderson 28'121 2,571,525 10/ 1951 Blitstein 1l1 2,649,877 8/1953 Renn 15638(l 3,022,814 2/1962 Bodine 156-73 3,101,634 8/1963 Cooper 15673 BENJAMIN R. PADGETT, Primary Examiner -E. E. LEHMANN, Assistant Examiner 

